Sometimes when people are using old painful versions of samba you can’t use the encrypted passwords to talk to the remote server. You just get a complaint that the password is incorrect all the time, even though you keep typing the damned thing in correctly.
What you need in this case is an nsmb.conf file in ~/Library/Preferences/. It needs to contain a stanza:
[host you care about] minauth=none
For every host that is not using high-falluting authentication. It would be better to not use a default entry here, as we want to ensure that the default attempt is not to try with unencrypted communications.